Defending champion Alberto Contador and his main rival Andy Schleck have yet to properly test each other in the Tour de France 2011. They have been too busy avoiding serious injury in nine days of manic racing, which came to a temporary halt with Monday's rest day.

Although Contador has already crashed twice, the Spaniard was somewhat lucky to escape with just a bruised right knee, given that several other riders had to retire with more serious injuries. They include Kazakh star Alexandre Vinokourov (broken thighbone) and British hope Bradley Wiggins (broken collarbone).

"It may be the hardest Tour de France start I have experienced," said Schleck, who rides for Leopard-Trek. "A lot of nervy stages."

Contador is concerned he may lack his trademark uphill acceleration when the big climbs come later this week. He trained with teammates on Monday morning, but knows he can only really asses his condition when the race resumes Tuesday.

"I'm a bit worried because with a knee injury you can't ride with the same rhythm and the same frequency of pedaling as usual," said Contador, who has swelling on the inside of his right knee. "I want to remain optimistic it will get better before the first Pyrenean stage, but I have no idea how the knee will respond."

Schleck, the Tour de France runner-up to Contador in the past two years, is grateful to have enjoyed more luck than his rivals.

Contador crashed early in Sunday's ninth stage - which later accounted for Vinokourov - and banged the same knee he hurt falling on stage 5.

"It's sad to see to what degree luck has influenced the course of the race," Schleck said Monday and added "You can avoid crashes to a certain extent, by staying at the front of the bunch and being very aware of possible dangers."

But no race strategy could account for the fact a Tour de France car knocked Spanish rider Juan Antonio Flecha into Dutchman Johnny Hoogerland in a shockingly careless incident on Sunday.

"It's really out of your hands," Schleck said and continued "We feel very fortunate that none of our team members was involved in a big crash."

Flecha recalled the incident.

"I was bleeding everywhere, I saw Johnny laying there, and I said 'Wow,'" Flecha said Monday.

With Contador's sore knee still bothering him, Schleck will gauge the three-time champion's true fitness in the Pyrenees climbs starting Thursday. Schleck is in the driving seat as Contador needs to make up time, a role reversal from last year when Contador beat Schleck by 39 seconds to win his third Tour de France.

"I'm not as fresh as the previous years," Contador said and continued "But I don't want to use this as an excuse."

Contador lost valuable time on the first day this year, when he was stuck behind a crash that split the peloton while Schleck stayed ahead of it.

Like the toss of a coin, Schleck got the good call that day. He is 1 minute, 30 seconds ahead of Contador in the overall standings, and 11 seconds behind two-time Tour runner-up Cadel Evans of Australia, the other main GC contender.

"So far so good, the team has been great, keeping me out of trouble, and if it could continue like this I would be very, very happy," Evans said.

After Monday's rest day, there are two semi-flat stages for sprinters before riders enter the Pyrenees on stage 12, with its colossal climb up Col du Tourmalet - one of the Tour's most famed and feared ascents.

That stage is so demanding it could decimate the field.

Frenchman Thomas Voeckler leads the race after taking the yellow jersey from Thor Hushovd, while Spaniard Luis Leon Sanchez, who won stage 9, is second overall. But neither is a Tour contender and both should soon wilt.

Thursday's stage from Cugnaux to Luz-Ardiden lasts a horribly long 211 kilometers (131.1 miles) and ends with a mammoth climb up Luz-Ardiden.

Like the Tourmalet, Luz-Ardiden is so tough it is known as an HC - or 'Hors Categorie' - climb, meaning it is even harder than a category 1 climb and is therefore beyond classification.

The pain does not stop there.

Friday's 13th stage from Pau to Lourdes features an HC trek up Col d'Aubisque, followed by a hair-raising 40-kilometer (24.8-mile) descent to the line.

Saturday's 14th stage starts from Saint-Gaudens and is harder than the previous two - an intense day featuring two nasty category 1 ascents up Col de la Core and Col d'Agnes, and finishing with a long HC climb up to Plateau de Beille.

"There will be a big shake-up at Plateau de Beille," Schleck said. "If there's a chance for us, we'll take it."

Stay tuned to Roadcycling.com and Roadcycling.mobi as the Tour de France continues.